Onslaught is a fictional character that appears in comic books published by Marvel Comics. The character first appeared in cameo X-Man #15 (May 1996), his first full appearance in X-Men vol. 2, #53 (June 1996). Onslaught was co-created by writers Scott Lobdell, Mark Waid, and artist Andy Kubert. He was written and introduced as a villain that was part of the effect of events in the 1993 Fatal Attraction storyline. Onslaught's introduction into X-men storylines caused its own cross over event across multiple Marvel comic book titles (several Fantastic Four issues, X-men and Uncanny X-men issues, and the Cable issues).

Onslaught was written as a sentient psionic entity created from the consciousness of two mutants: Professor Charles Xavier and Magneto. During a battle between the X-Men and Magneto's Acolytes, Professor Xavier used his telepathic powers to shut down Magneto's mind, rendering him catatonic. It was explained through the Onslaught crossover series that the darkest aspect of Magneto's mind escaped into Xavier's subconscious, where it 'merged' with Xavier's own darker nature to eventually grow into a separate persona of its own.

Onslaught is a sentient psionic entity created from the consciousness of two extremely powerful mutants: Professor Charles Xavier and Magneto. During a battle between the X-Men and Magneto's Acolytes, Wolverine slashed Magneto, and in response, Magneto ripped out the Adamantium from his bones, injuring Wolverine so much that even his healing factor had trouble healing him. For Professor Xavier, this was the limit. Having tolerated every one of Magneto's evil actions, even his recent actions that had killed hundreds of people across the globe in a single day, he finally snapped. He used his telepathic powers to shut down Magneto's mind, rendering him catatonic. During the psionic contact, Magneto's anger, grief, and lust for vengeance entered Professor Xavier's consciousness, co-mingling with every long-suppressed negative feeling the professor had endured during the last 30 years. This aggregation resulted in a separate personality within Professor Xavier, the being known as Onslaught.

Onslaught was a sentient psionic entity created from the consciousness of Professor Charles Xavier and Magneto. During a battle between the X-Men and Magneto's Acolytes, Magneto used his powers to rip the adamantium from Wolverine's skeleton, causing such extensive injuries that his healing factor burned itself out. Xavier was so unhinged with anger over the brutality of Magneto's assault against Wolverine that he used his telepathic powers to shut down Magneto's mind, rendering him catatonic. During the psionic contact, Magneto's anger, grief and lust for vengeance entered Xavier's consciousness; commingling with every long-suppressed negative feeling Xavier had endured during the last 30 years. This aggregation resulted in the being known as Onslaught.

Onslaught remained dormant for some time. Gradually, Xavier's frustration with his dream of mutant-human harmony began to increase, exacerbated by the daily growth of anti-mutant hysteria, the deaths of dozens of mutants from the lethal Legacy Virus, and his own failed attempt to rehabilitate Sabretooth. Xavier reached his breaking point when anti-mutant humans killed a young mutant near the grounds of the Xavier Institute for Higher Learning, the secret base of the X-Men. It was at this point that Onslaught awakened within Xavier and began to manifest himself to others.[volume & issue needed]

Following an encounter with Juggernaut, Onslaught invaded a government-sanctioned Sentinel base. He downloaded the current specifications for the mutant-hunting androids and erased portions of the memories of the employees working in the clandestine factory. Onslaught first manifested himself to the X-Men themselves when he challenged the teleporter Gateway to test Cyclops, Storm, Wolverine and Iceman, by kidnapping them and sending them to face off against his agent Post. Soon after, while hiding in Xavier's mind, Onslaught encountered X-Man. He pulled the Professor's body from the astral plane. Through X-Man's actions, Onslaught was able to escape Xavier's mind and move independently. Onslaught also sought out Jean Grey, hoping to convince her to join his cause with the offer of power rivaling that of the Phoenix Force, while also revealing damaging information about Professor Xavier, such as a long forgotten attraction the Professor had to Jean during the X-Men's early days. Jean resisted Onslaught, but was defeated by him, and sent back to her physical body, with only a fleeting memory of what had happened as well as the name "Onslaught" telepathically branded on her forehead. After taking full possession of the Professor's mind and body, Onslaught-as-Xavier called together the X-Men. When they resisted his plan to turn them into soldiers fighting a total war against humans, Onslaught revealed himself to the X-Men and attempted to destroy the outlaw adventurers. Bishop, remembering childhood stories of a traitor betraying and killing the X-Men, began to realize that the guilty party was Xavier as Onslaught. Bishop rescued his teammates, but Onslaught escaped, taking Xavier's body with him.[volume & issue needed]

Once free, Onslaught created a childlike psionic projection named Charles to gain the trust of Franklin Richards. Onslaught succeeded in capturing the child despite a rescue attempt by Mister Fantastic and Invisible Woman. Now carrying Franklin and Xavier, Onslaught captured X-Man, intending to use his raw psionic power to fuel Onslaught’s plans to transform the human race into a collective consciousness. Onslaught returned to New York, reprogramming the Sentinel robots to obey his commands and form a protective circle around Manhattan, sealing off the island from the rest of the world.[volume & issue needed]

The X-Men, the Fantastic Four and the Avengers joined forces to challenge Onslaught. Their first confrontation with the entity and his minions resulted in the rescue of Xavier, reducing Onslaught to a mass of psionic energy contained within his armor - unfortunately, this also prevented Xavier from influencing the villain with his better nature. A second and final confrontation occurred at Onslaught's Central Park citadel where the heroes made a number of attempts to free Franklin and X-Man from Onslaught's armor. During their next assault, X-Man Jean Grey used her telepathy to suppress the part of the monstrous Hulk's mind that contained the rationality of his alter ego, Dr. Bruce Banner. With his new, nearly-feral intelligence pushing his rage - and thus, his strength - to unbelievable levels, the Hulk battled Onslaught and tore apart his armor. The resulting explosion of psionic energy separated Banner and the Hulk, and Onslaught was left as an energy being, immune to most physical harm. Onslaught then used Franklin's powers to create a second sun that would destroy the heroes and Manhattan.[volume & issue needed]

In desperation, Thor flew into the energy being, disrupting Onslaught's form. Realizing that Thor's efforts alone were insufficient to destroy their adversary, the non-mutant members of the Avengers and the Fantastic Four entered the energy field. The X-Men were unable to do likewise, as it was theorized that if Onslaught, a being of mutant origin, came to possess a mutant host, he would become unstoppable. Onslaught dissolved, seemingly destroyed, along with the heroes who had thrown themselves into the rift. The remaining Sentinels were disabled, Franklin and X-Man were rescued, and Manhattan was returned to normal. Later, it was revealed that the Avengers and the Fantastic Four did not die, as had been surmised. Rather, the heroes were reborn in a pocket universe created by Franklin. The Avengers and the Fantastic Four returned to their rightful home months later, possessing only hazy memories of their time on Counter-Earth.[volume & issue needed]

A five-issue miniseries was issued in late 2006 to celebrate the tenth anniversary of the "Onslaught" storyline, titled Onslaught Reborn, by writer Jeph Loeb and artist Rob Liefeld. Onslaught Reborn features the return of the villain and addresses unresolved plot threads;[1] this event is set after the "Decimation" and "Civil War" storylines.[2]

After Scarlet Witch used her powers to de-power most of Earth's mutants, the powers of Charles Xavier and Magneto collided to reform Onslaught, whose consciousness lingered after his defeat. Onslaught swore revenge on the young Franklin Richards and any other hero that he despised, manifesting as a monstrous version of his previous form with a skull-like face. He first took control of both the Human Torch and Mr. Fantastic in an attempt to kill Franklin, but was soon interrupted by the Invisible Woman and the Thing, who saved Franklin. Franklin ran to Counter-Earth, but Onslaught followed.[3]

As Onslaught appeared in Counter-Earth he became larger, and regained his Magneto-like mask. He soon encountered the Avengers and was presumed defeated after he fell into the ocean. Instead of worrying about Onslaught, the Avengers questioned Franklin's credibility, as Franklin claimed to be the son of both Mr. Fantastic and the Invisible Woman. On Counter-Earth Mr. Fantastic and the Invisible Woman were not married and did not have children. Shortly after this, Thor was assaulted by an Onslaught-possessed Hulk, who battled Thor to determine which of the two was more powerful. Onslaught switched between the bodies and possessed Thor, who struck the Hulk with lightning. As Thor was about to strike again, he dropped his hammer, as Onslaught was not worthy to carry it. Onslaught switched back to the Hulk, and punched Thor into the atmosphere. Onslaught was assaulted by the Avengers before he could pick up Thor's hammer. Captain America ordered the Human Torch and Iron Man to rescue Thor, telling them they had about sixty seconds for the rescue. They raced to save him, and Johnny took Thor back to the Baxter Building, where Mr. Fantastic discovered that Franklin really was his son. In the battle, Captain America ordered Hawkeye to find Onslaught, and confronted Hawkeye with the fact that Wolverine was hiding in Hawkeye's costume. The Avengers continued to battle the Hulk, while Captain America was thrown into a building. Iron Man, from the atmosphere, charged down at the Hulk at full speed, hoping that Bruce would forgive him someday. He punched the Hulk, knocking him out. He and Captain America assessed their next move until Onslaught possessed Iron Man and attacked Captain America. Back at Avengers Mansion, Rikki Barnes was babysitting Franklin when Loki, Executioner, Scarlet Witch, Enchantress, and Ultron V surprised them with an offer to help defeat Onslaught. On a balcony, an invisible Ant-Man and the Invisible Woman let themselves be known, as Sue refused to let the villains cause Franklin any harm.[3]

After a brief skirmish, the heroes and villains decided to work together to defeat Onslaught. Rikki "Bucky" Barnes defeated Onslaught using a Fantasticar to send both Barnes and Onslaught through the Negative Zone barrier in the Fantastic Four's lab, trapping them. Franklin returned home, Bucky found herself on Earth 616, and Onslaught was last seen floating outside the Area 42 Prison in the Negative Zone.[3]

Rikki Barnes, now known as Nomad, began having strange and vivid nightmares from deep in the jungles of South America. When her teammate Toro is kidnapped just like she dreamed, she begins to suspect that her nightmares are something more sinister than she first thought. Later, while investigating Corporate Conglomerate Roxxon for illegal weapons systems, the Secret Avengers come across the plans for Project Power, a new and incredibly deadly power source being secretly developed in the Colombian rainforest. As the Secret Avengers investigate the facility, Beast and Ant-Man find the source of the mysterious energy source to be from the Negative Zone. As Rikki races inside the facility to locate Toro, she stumbles into the control room instead, where the sinister voice of her dreams beckons and reveals itself to be Onslaught.[4]

Possessing Rikki's body, Onslaught reveals that the real Rikki had, in fact, died in the Negative Zone; his current host was just a construct made by Onslaught himself so he could use the energy he had stored in her as an anchor to pull himself back into the main Marvel Earth. The revelation that Rikki had been sent to the main Marvel Earth solely to serve as Onslaught's tether forced Rikki to fight back to prove he was wrong. Eventually, Rikki had Gravity kill her so that Onslaught could not return and destroy Earth.[5]

Despite Rikki's apparent death, Steve Rogers began to have nightmares similar to the ones Rikki had before, suggesting that enough of Nomad's (and Onslaught's) energy may have survived to escape death and now seek a new way to return to the main Marvel reality.[6]

A clone of Red Skull stole the brain of the deceased Professor X and grafted part of Xavier's brain to his own, giving him Professor X's powers.[7]

In the lead-up to the AXIS storyline, Red Onslaught is created when Magneto kills the Red Skull while filled with hate after killing the S-Men.[8]Scarlet Witch and Doctor Doom attempt to defeat the Red Onslaught by using their magic to perform a moral inversion on him that would allow Professor X to control the amalgamation, but their efforts backfire, causing all the heroes and villains present during the confrontation to morally invert from their usual behavior.[9] With the Skull now reverted to a human body that is identified as the 'White Skull'- implied more than once to be Professor X in control of the body once again- he is hidden from the inverted Avengers by Edwin Jarvis until the aged Steve Rogers can retrieve him.[10] Working with the inverted villains- now referring to themselves as the 'Astonishing Avengers'- and with the resurrected Brother Voodoo now possessing the inverted Scarlet Witch, the White Skull is able to undo the inversion, although he simply returns to his Red Skull persona rather than Onslaught.[11]

Onslaught's powers were well over that of Omega Level. In his first form (when he was one with Xavier), Onslaught showed a wide variety of abilities including immeasurable strength, and incredible resistance and endurance. Onslaught's psionic powers appeared limitless, appearing to surpass even that of Xavier in his right mind. He was especially powerful in the Astral Plane, where he appeared to have god-like abilities. Even Jean Grey's powers were completely useless against him. From what has been seen, he seems to have total mental control over anyone or anything he wishes, ranging from altering one's perception to believe they are someone or somewhere else (he demonstrated this by making Wolverine believe he was a wolf pup, and making Storm think she was a child), to most conceivable forms of telekinesis. Onslaught also possessed many forms of energy projection, all of which are at high levels of power. Even at his initial level he was able to punch the Juggernaut unconscious across North America, and even rip the Crimson Gem of Cyttorak out of his body.

After fully evolving into his own, separate consciousness and having Professor X ripped from him in the Astral Plane, Onslaught evolved into a second form, less resembling Magneto and looking more like a cybernetic monster. In this form, thanks to adding the full potential of Franklin Richards and Nate Grey combined, his powers were increased to godlike levels, including the ability to mass-manipulate (his complete takeover of all the Sentinels), create and reshape matter at will (shown when he created his citadel, and when he created a second sun to destroy Earth), and an apparent omniscience (as evidenced when he easily thwarted an attempt to sneak into his citadel). He could use his combined reality-warping and telekinetic abilities to boost his physical strength to the point that he was able to go toe-to-toe in a physical fight with the Hulk even after the Hulk's mind had been blanked and his strength and rage set to incredible levels thanks to Jean Grey 'shutting down' the subconscious influence that Bruce Banner normally exerted over the Hulk to stop him going too far.

For a time, Onslaught had these powers while still in his first form; the majority of these came from the absorption of Nate Grey and Franklin Richards. In the end, Onslaught's true body was revealed to be a mass of pure, psionic energy that was immune to all forms of physical attacks.